The action of digastric muscle is:

 # The action of digastric muscle is:

A. Depression of mandible

B. Protrusion of mandible

C. Side to side movement of the mandible

D. Depressing the floor of the mouth

The correct answer is A. Depression of mandible.

The digastric muscle is involved in any complex jaw action such as speaking, swallowing, chewing and breathing.

When the digastric muscle contracts, it acts to elevate the hyoid bone.

If the hyoid is being held in place (by the infrahyoid muscles), it will tend to depress the mandible (open the mouth).

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Nasopharynx is connected to:

 # Nasopharynx is connected to ______________ through pharyngotympanic tube.

A. Middle ear

B. Outer ear

C. Middle meatus

D. Semilunar canals

The correct answer is A. Middle ear.

The middle ear lies in the temporal bone, where the chain of three ear ossicles connect the tympanic membrane to the oval window. The middle ear cavity communicates with the nasopharynx via the eustachian tube, which allows air pressure to be equalized on both sides the tympanic membrane. 

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Nasal cavity receives blood supply from:

 # Nasal cavity receives blood supply from:

A. Facial artery

B. Maxillary artery

C. Ophthalmic artery

D. All of the above

The correct answer is D. All of the above

Nasal cavity receives blood supply from superior labial, a branch of facial artery; anterior posterior ethmoidal , a branch of ophthalmic artery; Sphenopalatine and greater palatine, a branch of maxillary artery. So, the correct answer is D. All of the above.

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Superior meatus of nose has opening of:

 # Superior meatus of nose has opening of:

A. Middle ethmoidal sinus

B. Anterior ethmoidal sinus

C. Posterior ethmoidal sinus

D. Middle ethmoidal sinus and Anterior ethmoidal sinus

The correct answer is C. Posterior ethmoidal sinus. 

Meatuses are passages behind the overhanging conchae. 

INFERIOR MEATUS

- Largest of all three

- Nasolacrimal duct opens into it. This opening is guarded by lacrimal fold or Hassner valve.

- Lies underneath inferior concha

MIDDLE MEATUS

- Lies underneath middle concha

- Most air sinuses open into it: Frontal air sinus, Maxillary Sinus, Middle ethmoidal sinus and anterior ethmoidal sinus

SUPERIOR MEATUS

- Below superior concha

- Shallowest of all the three

- Posterior ethmoidal sinus opens into it

# Nasolacrimal Duct opens into Inferior meatus of nasal cavity.

# The frontal paranasal sinus drains into the middle meatus of the nasal cavity.

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Superior sagittal sinus continues as:

 # Superior sagittal sinus continues as:

A. Inferior sagittal sinus

B. Straight sinus

C. Right transverse sinus

D. Left transverse sinus

The correct answer is C. Right transverse sinus.

Superior sagittal sinus continues as right transverse sinus. Inferior sagittal sinus ---> Straight sinus. 

Straight sinus ---> Left transverse sinus. 

Transverse sinus -----> Sigmoid sinus

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Cricothyroid muscle is supplied by:

 # Cricothyroid muscle is supplied by:

A. External laryngeal nerve

B. Internal laryngeal nerve

C. Recurrent laryngeal nerve

D. A direct branch from vagus nerve

The correct answer is A. External laryngeal nerve. 

All the muscles of  larynx are supplied by recurrent laryngeal nerve EXCEPT Cricothyroid. Cricothyroid is supplied by External laryngeal nerve. Recurrent laryngeal nerve supplies:

a) All intrinsic muscles of larynx EXCEPT Cricothyroid

b) Sensory nerves to the larynx below the level of the vocal cords.

c) Cardiac branches to the deep cardiac plexus.

d) Branches to the trachea and oesophagus.

e) Inferior constrictor

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The space between the vocal folds is called:

 # The space between the vocal folds is called as:

A. Rima vestibuli

B. Rima glottidis

C. Rima laryngeus

D. Rima arytenoid

The correct answer is B. Rima glottidis.

Within the cavity of larynx there are two folds of the mucus membrane on each side. The upper fold is the vestibular fold and the lower fold is the vocal fold. 

The space between the right and left vestibular folds is the rima vestibuli; and the space between the vocal folds is the rima glottidis. 

The vestibular and vocal folds divide the cavity of the larynx into three parts: 

1. The part above the vestibular fold is called the vestibule of the larynx.

2. The part between the vestibular and vocal folds is called the sinus or ventricle of the larynx. 

3. The part below the vocal folds is called the infraglottic part. 

The sinus of Morgagni or ventricle of the larynx is a narrow fusiform cleft between the vestibular and vocal folds. The anterior part of the sinus is prolonged upwards as a diverticulum between the vestibular fold and the lamina of the thyroid cartilage. This extension is known as the saccule of the larynx. The saccule contains mucous glands which help to lubricate the vocal folds. 

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